Avaliação das propriedades físicas, reológicas e do processo de mistura na incorporação de borracha reciclada de pneus como modificador de ligantes asfálticos

Abstract

The Bitumen has great influence on the behavior of mixtures asphalt, through this material, it’s conferred properties of cohesion, rutting and fatigue resistance to the pavement. However, with the increase in traffic and load capacity of commercial vehicles, the need for greater performance in face of these requests is highlighted. Some research’s purpose addiction of polymers, rubbers and other materials in Bitumen matrix in order to beneficiate your performance, so the present study aims to modify conventional petroleum asphalt cements with the addition of crushed rubber from recycled tires. Three levels of incorporation 15, 18, 21% were evaluated in relation to the mass of bitumen, moreover for the 15% samples the variation of digestion time of 2, 4, 6 hours was also investigated. The Penetration, Softening Point, Elastic Recovery and phase separation tests were performed following the specification standard. For the rheological characterization were performed tests to obtain the masters curves of Dynamic Shear Modulus and Phase angle, as well as the high temperature of PG classification of the samples in virgin state. The same steps were executed to short-term aging in Rolling Thin Film Oven Test (RTFOT) and long-term aging in Pressure Aging Vessel (PAV). In this aging states tests of damage quantification Multiple Stress Creep Recovery (MSCR) and Linear Amplitude Sweep (LAS) were performed to measure parameters of rutting and fatigue resistance, respectively. The incorporation of recycled rubber from tires promoted an increase in elastic recovery and the softening point, a decrease in penetration and good capacity for storage stability. In the rheological tests, it was identified, mainly, an increase in stiffness and a decrease in the phase angle at high temperatures, as well as an increase in PG at high temperature. The highlight in these results was in charge of the higher rubber levels (21%), indicating a performance improvement of rutting and fatigue resistance with the addiction of rubber, evidenced by MSCR and LAS analysis. Still the variation in digestion time produced little significant improvements in behavior. Finally, the mixing protocol caused the samples to stiffen with an increase in the dynamic shear modulus, indicating a certain degree of aging. For this reason, it is still necessary to understand the interaction between the rubber and the asphalt matrix to optimize the mixing process and obtain modified binders in the laboratory more efficiently.